1. Technical Field
The present invention relates to a liquid drug container and, more particularly, a liquid drug container used for preservation of liquid drugs or liquid cosmetics and so designed that the interior of the container is prevented from being contaminated by bacterium or microorganisms.
2. Background Art
In containers used for preservation of liquid chemicals or liquid cosmetics, an interior of the container is not aseptically isolated from the exterior. Thus, if the container is unsealed to bring it into use, the interior of the container is exposed to the atmosphere through a nozzle of the container. Thus, there is a fear that floating bacteria in the atmosphere may invade the interior of the container through the nozzle. On the other hand, if the nozzle is brought into contact with the skin during use, there is a fear that the interior of the container is easily invaded by bacterium or microorganism adhered to the skin. Further, as the liquid drug container of this kind, there have been used such containers that discharge a content thereof under pressure of a hand and restore to the original configuration after release of the pressure applied thereto. At the time of return to the original configuration, the deformed container sucks in the surrounding air. Thus, there is a fear that bacteria and microorganism in the atmosphere are sucked in the interior of the container along with the air flowing into the container.
Accordingly, the liquid drug containers of the prior art are at high risk of multiplication of bacteria or microorganisms in the container body as the invaded bacteria or microorganisms take active constituents contained in the drug, buffer solutions added for stabilizing the liquid drug, or solubilizing agent as nutrients.
For purposes of antisepsis, sterilization or antibacterial activity, it is common practice to incorporate various kinds of preservatives into the liquid drugs of the prior art to prevent multiplication of bacteria or microorganism even if the container is invaded by bacteria or microorganism. The generally known preservatives include antiseptics of quaternary ammonium salts exemplified by benzalkonium chloride and benzethonium chloride. However, such salts are limited in use because of their strong stimulation and cytotoxic effects. Particularly, they can not be used as antiseptics for liquid drugs applied to eye tissues or organs sensitive to stimulus.
In recent years, reports have been made on so-called chemical hypersensitivity, i.e., symptom of serious allergy to chemical compounds such as preservative. For that reason, some chemicals and cosmetics containing no preservative have been developed and put to practical use. However, if the chemicals or cosmetics do not contain any preservative, it is impossible to ensure aseptic conditions after unsealing. This necessitates packaging of a dosage of such a chemical solution or a liquid cosmetic in a single disposable container, entailing an increase in production costs and space-consuming. Thus, the chemicals and cosmetics do not contain any preservative fail in popularization.
On the other hand, it has been proposed to make the container with a plastic deformable body (Examined Japanese utility model publication No. S63-184037, Japanese translation of PCT international application No. 2001-521865) to prevent invasion of floating bacteria or microorganism, which results from inflow of the atmosphere which occurs at the time of restoring of the pressure-deformed container to its original state by the pressure release after discharge of the liquid drug.
However, even if the container is of plastic deformable body, there is no change in the fact that the medical solution contained therein is exposed to the atmosphere through a dispensing nozzle. Thus, it is impossible to completely prevent invasion of bacteria and microorganism.
Further, there have been proposed some containers of the kind wherein the nozzle is provided with a filter to prevent invasion of bacteria and microorganism, which may take place when the liquid drug remained in the nozzle is returned to the container body after use, or when the elastically deformed container is restored to its original state by the pressure release (cf. Examined Japanese utility model publication No. S35-592, Examined Japanese utility model publication No. S35-31875).
However, even if the nozzle is provided with a filter, it is impossible to trap unobservable bacteria or microorganism since the filter, which allows both liquid and gas to pass therethrough, generally has a large bore size.
To this end, it has been proposed to provide the container with a hydrophilic filter or a hydrophobic filter that enable to trap unobservable bacteria or microorganism. However, if the filter is a hydrophilic filter, it is unable to allow the pressure-deformed container to restore to its original configuration since the hydrophilic filter prevents flow of the gas though it allows the liquid to pass through.
In order to allow the container to restore to its original configuration, it has been proposed a container provided with a hydrophobic filter allowing the atmosphere to flow in the container ((cf. Examined Japanese Patent publication No. H03-61461).
Since the nozzle hole serves as an air hole, the hydrophobic filter limits inflow of the atmosphere when the liquid drug that flows back from the nozzle is retained on the hydrophobic filter. Thus, the pressure-deformed container can not be restored to the original configuration.
Further, there is a container so designed as to block inflow of the atmosphere into the container to prevent invasion of bacteria (cf. Published Japanese Patent application No. JP2002-80055A).
As shown in FIG. 14, a container 102 of an embodiment of the above prior art includes a plug body 103 fitted in a mouth thereof. The plug body 103 is a top-closed cylindrical member, into which a top-closed fitting member 134 is fitted to form a space between a top of the plug body 103 and a top of the fitting member 134. The plug body 103 is provided with a nozzle 131 at a central part of the top thereof, while the fitting member 134 is provided with a valve hole 106 at a central portion of the top thereof. A filter 107 is arranged on a bottom side of the nozzle 131, and a check valve 108 is arranged on a upper side of valve hole 106. A space formed between the filter 107 and the check valve 108 serves as a space 109 holding a liquid drug.
In use, by exerting pressure on the container 102 with hand after taking off an outer cap 140, the liquid drug in the container passes through the valve hole 106, pushes the check valve 108 open, fills the holding space 109, and spouts from the nozzle 131. By loosing the pressure on the container 102, the container 102 begins to restore to the original configuration and produces a negative pressure, so that the discharge of the liquid drug is stopped. At the same time, the check valve 108 is closed and thus the container 102 is prevented from inflow of the ambient air even if the air flows in through the nozzle 131.
However, there is a fear that the liquid drug stays in nozzle 131, which in turn causes a fear of bleeding of bacteria in the tip portion of nozzle 131 being in direct contact with the ambient air. The thus polluted liquid drug is used for a patient in the next use. Even in the embodiment of the prior art, it is impossible to keep aseptic conditions of the liquid drug.